Table 1.

Utilization of hexoses and HP by wt L. monocytogenes (wt) and ΔprfA and Δhpt derivatives

	Glc	G1P	G6P	Fru	F6P	Man	M6P
wt	+	+	+	+	+	+	+
ΔprfA	+	−	−	+	−	+	−
ΔprfA + prfA	+	+	+	+	+	+	+
Δhpt	+	−	−	+	−	+	−
Δhpt + hpt	+	+	+	+	+	+	+

The assays were performed at 37°C in PrfA-activating conditions (see Materials and Methods) in phenol red broth supplemented with the test sugar as the sole carbon source. Use of the sugar is indicated by acidification of the medium. +, positive reaction at 24 h; −, negative reaction after prolonged (>4 wk) incubation. Hexoses: glucose, Glc; fructose, Fru; and mannose, Man. In-frame deletion of prfA, the gene coding for PrfA, was carried out by using the same strategy as that used for Δhpt (229 of the 237 codons of prfA were removed). For transcomplementation of ΔprfA bacteria, previously described plasmid constructs were used (6).